The present invention generally relates to the maintenance of air conditioning or refrigeration systems and, in a preferred embodiment thereof, more particularly relates to apparatus and methods for placing an additive fluid into the refrigerant circuit of an air conditioning system.
In the typical air conditioning or refrigeration system it is often necessary to place an additive fluid (normally a liquid) into the refrigerant circuit portion of the system to maintain the performance of the system at a satisfactory level. Examples of additive fluids placed in refrigerant circuits include compressor oil, stop-leak liquid, acid neutralizers, drying agents, and ultraviolet colored leak-finder liquid.
Additive fluids of these and other types are conventionally placed in refrigerant circuits by one of four methodsxe2x80x94namely, (1) the refrigerant circuit is opened, and an additive liquid is simply poured into the circuit; (2) the additive fluid is placed in a container along with pressurized refrigerant and is expelled with the pressurized refrigerant into the circuit; (3) the additive fluid is placed in an in-line storage device, and pressurized refrigerant is flowed through the storage device to force the additive fluid into the circuit along with the pressurized refrigerant; or (4) the additive fluid is injected into the circuit using a mechanical piston to force the fluid into the circuit.
These conventional techniques carry with them certain known problems, limitations and disadvantages. For example, to simply open the refrigerant circuit and pour the additive in can undesirably cause release of refrigerant to the atmosphere, and can also undesirably introduce contaminating air into the circuit. Packaging an additive fluid in a container with pressurized refrigerant to be forcibly injected into the circuit is also undesirable due the expense of adding refrigerant to the container as a propellant, the safety concerns inherent in a pressurized container structure, and the need to match the refrigerant propellant with the type of refrigerant within the circuit. Placing the additive fluid in an in-line device requires that the refrigerant forced through the device match the refrigerant in the circuit to avoid contamination of the circuit. Injecting additive fluid into a refrigerant circuit using a mechanical piston device tends to be a somewhat cumbersome task requiring specialized packaging and/or equipment.
As can readily be seen from the foregoing, a need exists for improved apparatus and methods for placing an additive fluid into a refrigerant circuit. It is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a specially designed vessel or canister is provided for use in placing an additive fluid, representatively an additive liquid, into the refrigerant circuit of an air conditioning or refrigeration system, representatively an automotive air conditioning system. In a preferred embodiment thereof, the vessel has an interior communicatable with a suction line portion of the refrigerant circuit, the vessel interior being partially filled with an additive liquid, being partially evacuated to a vacuum pressure less than that of the suction line portion during operation of the air conditioning system, and being substantially devoid of refrigerant.
According to a first method of utilizing the partially evacuated vessel, the interior of the vessel is initially communicated with the interior of the suction line portion during operation of the air conditioning system, representatively using a refrigerant recharge hose assembly, whereupon the greater vacuum pressure in the suction line portion of the refrigerant circuit draws the additive liquid into the suction line portion.
According to a second method of utilizing the partially evacuated vessel, the refrigerant circuit is emptied and a vacuum pressure is created therein which is greater than the vacuum pressure within the vessel. The vessel is then communicated with the interior of the refrigerant circuit, representatively using a refrigerant recharge hose assembly, whereupon the greater vacuum pressure within the emptied refrigerant circuit draws the additive fluid into the refrigerant circuit.
According to a third method of utilizing the partially evacuated vessel, the interior of the vessel is initially communicated with the interior of the suction line portion, representatively using a refrigerant recharge hose assembly, while the air conditioning system is turned off and a positive pressure exists in the interior of the suction line portion. The positive pressure within the suction line portion forces refrigerant therefrom into the vessel, thereby positively pressurizing its interior. Next, the air conditioning system is turned on to create a negative pressure within the suction line portion, thereby drawing the refrigerant and additive liquid from the positively pressurized canister interior into the suction line portion.
The provision and use of the specially designed partially evacuated vessel provides a variety of advantages over conventional pressurized canisters containing refrigerant and liquid additive. For example, since there is no refrigerant in the vessel, the same additive liquid-containing vessel can be used with a wide variety of air conditioning or refrigeration systems that utilize different types of refrigerantsxe2x80x94the vessel does not have to be xe2x80x9cmatchedxe2x80x9d to a particular type of refrigerant in a circuit in order to avoid contamination thereof by a different type of refrigerant within the vessel.
Moreover, since refrigerant is not packaged within the vessel, the material cost of the partially filled vessel is substantially reduced. Additionally, since there is no refrigerant disposed within the as-manufactured vessel it cannot leak refrigerant into the atmosphere, and the lack of pressurized refrigerant within the as-manufactured vessel renders it safer to ship and store.